1. Field of the Invention
The present invention relates to a method of manufacturing a piezoelectric element that deforms according to a voltage applied thereto, a manufactured piezoelectric element, a piezoelectric actuator with the piezoelectric element, and a head suspension with the piezoelectric actuator.
2. Description of Related Art
Small-sized, precision information devices are rapidly advancing, and for use with such devices, needs for micro-actuators capable of conducting positioning control for very small distances are increasing. Such micro-actuators are highly needed by, for example, optical systems for correcting focuses and inclination angles, ink-jet printers for controlling ink heads, and magnetic disk drives for controlling magnetic heads.
The magnetic disk drives increase storage capacity by increasing the number of tracks per inch (TPI), i.e., by narrowing the width of each track on a magnetic disk.
Large-capacity magnetic disk drives, therefore, need an actuator capable of precisely positioning the magnetic head within a minute range across tracks.
To meet the need, Japanese Unexamined Patent Application Publication No. 2002-184140 discloses a head suspension with a dual actuator system. The dual actuator system employs a piezoelectric actuator in addition to a usual voice coil motor that drives a carriage to which the head suspension is attached. The piezoelectric actuator includes a piezoelectric element arranged between a base plate and a load beam of the head suspension.
According to this related art, the voice coil motor turns the head suspension through the carriage, and in addition, the piezoelectric element deforms in proportion to a voltage applied thereto, to minutely move the magnetic head at the front end of the load beam in a sway direction (a widthwise direction of the load beam) relative to the base plate. The dual actuator system involving the voice coil motor and piezoelectric element is capable of precisely positioning the magnetic head to a target position on a magnetic disk.
In order to manufacture the piezoelectric element, the piezoelectric element is cut out from a base material first. When cutting the piezoelectric element, peripheral end faces are formed to define a peripheral shape of the piezoelectric element. It, however, is easy to produce particles from the cut peripheral end faces of the piezoelectric element. A head suspension with the piezoelectric element may damage a magnetic disk drive in which the head suspension is attached, so that the particles enter into a gap between a slider of a magnetic head and a magnetic disk rotating at high speed.
To cope this problem, International Patent Application Publication No. WO2009/099438 discloses a coating technique of peripheral end faces of a piezoelectric element when manufacturing it.
The related art cuts a base material to form a plurality of piezoelectric elements that are arranged in a grid and separated by grooves. Each groove defines a gap between opposing peripheral end faces of adjacent piezoelectric elements. The related art applies polymer to the gaps with use of an ink-jet method to form coatings on the peripheral end faces of each piezoelectric element, respectively.
The gap, however, is set about 50 μm that is too narrow to surely form the coatings on the opposing peripheral end faces of the adjacent piezoelectric elements with the ink-jet method. If the gap widens to surely form the coatings, it deteriorates material yield.
A piezoelectric element may be individually picked up to surely form coatings on peripheral end faces thereof. This deteriorates the production efficiency of piezoelectric elements, thereby complicating to form coatings.